USN-3143-1: c-ares vulnerability

30 November 2016

c-ares vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 16.10
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS
  • Ubuntu 12.04 LTS


c-ares could be made to crash or run programs if it processed a specially crafted hostname.

Software Description

  • c-ares - library for asynchronous name resolves


Gzob Qq discovered that c-ares incorrectly handled certain hostnames. A remote attacker could use this issue to cause applications using c-ares to crash, resulting in a denial of service, or possibly execute arbitrary code.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 16.10
libc-ares2 - 1.11.0-1ubuntu0.1
Ubuntu 16.04 LTS
libc-ares2 - 1.10.0-3ubuntu0.1
Ubuntu 14.04 LTS
libc-ares2 - 1.10.0-2ubuntu0.1
Ubuntu 12.04 LTS
libc-ares2 - 1.7.5-1ubuntu0.1

To update your system, please follow these instructions:

In general, a standard system update will make all the necessary changes.